1. Field
This invention relates to medical treatment apparatus, systems and methods. More particularly, this invention provides apparatus, systems and methods for retrograde perfusion into a lumen of the body and even more specifically, for retrovenous perfusion into the coronary sinus region.
2. State of the Art
Retrograde perfusion of fluids such as drugs and blood either separately or together has been studied for a number of years. Retrograde perfusion has been considered desirable in order to supply drugs (e.g., free radical scavengers, calcium channel drugs, anti-arrhythmics such as xylocaine, tissue plasminogen activators (TPRA), streptokinease, edema reducing drugs and cardioplegia) and oxygenated blood to, for example, ischemic regions of the myocardium (heart) due to either a naturally occurring occlusion or an induced occlusion due to, for example, aortic cross clamping which is effected in order to perform some desired surgical procedure involving the myocardium.
Retrovenous perfusion into the coronary sinus while performing aortic cross clamping procedures or other similar surgical procedures typically involves some type of arrangement in which cardioplegic fluid(s) are delivered through catheters into the coronary sinus region. Since arterial flow to the myocardium is typically interrupted, the volume of retroperfusate introduced is not additive to the natural volume of venous blood exiting through the sinus region. Thus, retroperfusate is supplied under pressure to migrate in a retrograde fashion through the venous system and capillaries into the arterial system. See, e.g., R. A. Poirer, et al, Drip Retrograde Coronary Sinus Perfusion for Myocardial Protection During Aortic Cross-Clamping, The Journal of Thoracic and Cardiovascular Surgery, Vol. 70, Number 6, December 1975.
Retrovenous or retrograde perfusion in the coronary sinus region during a natural arterial occlusion has been suggested. Typical systems employ some type of pulsatile or synchronous delivery system to introduce retroperfusate into the myocardial sinus region. G. T. Smith, et al., Reduction of Infarct Size by Synchronized Selective Coronary Venous Retroperfusion of Arterialized Blood, The American Journal of Cardiology, Vol. 48, p. 1064 (December 1981). Synchronization may be effected through use of an R-wave signal obtained from a typical electrocardiogram (ECG or EKG) which is thereafter electronically processed and used to trigger (turn on and turn off) appropriate pumping structure to inject retroperfusate during diastole and to stop injection during systole. Synchronization has also been effected by monitoring venous or arterial system pressure to in turn synchronize pumping with diastole and systole. G. G. Geary, et al., Quantitative Assessment of Infarct Size Reduction by Coronary Venous Retroperfusion in Baboons, The American Journal of Cardiology, Vol. 50 (December 1982). S. R. Gundry, Modification of Myocardial Ischemia in Normal and Hypertrophiced Hearts Utilizing Diastolic Retroperfusion of the Coronary Veins, J. Thoracic & Cardiovascular Surgery, pages 659-669 (May 1982). That is, during systole (contraction of the myocardium) pumping is interrupted or stopped in order to allow blood to drain through the coronary sinus and into the vena cava. See: European Patent Application 8500326.7, filed Jan. 1, 1985 and published Aug. 7, 1985, publication number 0150960; and U.S. Pat. No. 4,459,977 (Pizon, et al.) During diastole (relaxation) pumping is initiated to introduce retroperfusate (e.g., drugs or oxygenated blood) into the sinus region under pressure sufficient to be transported in a retrograde fashion through the venous system and the capillaries in order to supply the drug and/or oxygenated blood thereto to reduce or minimize the ischemia resulting from the occlusion, and in turn, minimize the incidence and degree of necrosis and further to reduce the morbidity rate associated with myocardial infarction. See, e.g., S. Meerbaum, et al., Hypothermic Coronary Venous Phase Retroperfusion: A Closed-chest Treatment of Acute Regional Myocardial Ischemia, Circulation Vol. 65, No. 7, p. 1435 (June 1982).
An alternate system of a retrovenous myocardial treatment has been disclosed in which the coronary sinus is intermittently occluded to cause venous blood redistribution into ischemic regions for an unspecified period of time until a particular pressure is sensed or detected in the coronary sinus region upstream of the occlusion. The coronary sinus was thereafter opened to permit drainage and in turn a reduction of pressure in the sinus. Thereafter, the occlusion was again effected. The procedure employed a catheter with an inflatable balloon positioned within the coronary venous system. The catheter had a separate orifice or lumen to measure coronary venous pressure, W. Mohl, et al., Reduction of Infarct Size Induced by Pressure-Controlled Intermittent Coronary Sinus Occlusion, The American Journal of Cardiology, Vol. 53, p. 923 (Mar. 5, 1984).
Apparatus for retrovenous or retrograde perfusion, and more particularly catheters therefor, typically employ a balloon positioned proximate the proximal tip or end. The balloon is inflated in order to effect an occlusion in a lumen of the body, such as a coronary vein or the coronary sinus, so that retroperfusate may thereafter be pumped under pressure counter to the normal venous flow or normal flow in the lumen. The balloon is thereafter periodically collapsed or deflated in order to permit drainage and to avoid damage to the heart and/or venous system due to overpressure and for other purposes. See, U.S. Pat. No. 4,459,977 (Pizon, et al.) It has been reported that pressures in excess of 60 millimeters (mm) of mercury (Hg) in the coronary sinus, for example, may induce some type of pressure damage such as hemorrhage, ecchymosis or edema.
Heretofore it does not appear that the efficacy of retrovenous or retrograde perfusion is inherently effected by the amount of time and the pressure at which the retroperfusate is being urged backward counter to the flow in the particular lumen which has been occluded. Other factors, including the size of the lumen, the type of retroperfusate, the degree of normal flow such as normal arterial flow in the region to be retroperfused are also variables which have not collectively been considered to have an impact on the efficacy of the treatment. Further, it must be recognized that the venous system is naturally intended to remove undesirables including, for example metabolites, which physiologically must periodically be removed in order to maintain healthy tissue in the retroperfused region. Thus, effective and rapid drainage has not been viewed as desirable, especially to minimize the time when retroperfusion is interrupted. No structure to facilitate rapid drainage through the lumen that is occluded periodically and specifically past the balloon of a catheter introduced to perform retrograde or retrovenous perfusion is known or has been suggested. Also, no systems to maximize retrograde perfusion time under optimized but safe pressure have been suggested.
Some of the systems for retrograde perfusion disclosed heretofore have included apparatus external to the patient for supplying retroperfusate in accordance with pulsatile programs wherein the delivery schedule is synchronized to heart operation as determined through ECG signals or the periodic changes in diastolic and systolic blood pressure (e.g., U.S. Pat. No. 4,459,977). These systems do not therefore appear to maximize the retroperfusion therapy in the desired region under treatment because of what is presently believed to be insufficient migration or retroperfusion time. Apparatus which provides for extended automatic and safe operation and for practical long term retroperfusion therapy has not heretofore been available. Further, methods of retroperfusion therapy and methods for constructing certain preferred components of the retroperfusion system have heretofore not been known or available.